The present invention relates to a self-sealing plug for a catheter and a method for constructing the same.
Frequently in the field of medical practice, indwelling catheters are employed for large volume injections or removal of parenteral fluids. Typical examples of such uses are intravenous feeding and use of artificial kidneys. In such situations, it is very often necessary to administer small volume injections of drugs or samplings of parenteral fluids. In order to avoid the pain and discomfort accompanying direct insertion of hypodermic needles, injection ports are frequently provided in the catheter tubing or attached thereto by an adapter or other connecting device. The injection port is constructed so that injections can be made without affecting the sterility of the catheter or allowing parenteral fluids to enter and fill the catheter from the distal end and escape through the proximal end. Self-sealing injection ports which accomplish this purpose have been known in the art for some time. Several examples of self-sealing injection ports are disclosed in U.S. Pat. Nos. 3,898,988; 3,990,445; 4,187,149; 4,111,326; and 4,219,912. Other disclosures of possible relevance are U.S. Pat. Nos. 3,951,145 and 4,046,145.
In certain medical applications however, the injection port experiences higher than normal pressures. For example, during chemotherapy treatments, an infusion pump is used to slowly infuse cancer-treating drugs in the area of a tumor. Back pressures considerably higher than arterial pressures are typically developed by the pump inside the catheter. A manifold system is employed to permit injections of other drugs directly into the catheter without having to dilute such drugs by injection into the slowly infused chemotherapy liquids or necessitate the pain and discomfort of repeated hypodermic needle injections through the skin.
Especially in the field of chemotherapy, drug injections at a slow rate over a relatively long period of time must be administered for effective medical treatment. In such situations, it is highly desirable to allow the catheter to the left indwelling between chemotherapy treatments, thereby eliminating the need to reinsert and remove the catheter during each successive treatment. One problem which can be encountered when a catheter is left indwelling for relatively long periods is bacteria entering the distal end of the catheter and causing infection. It is therefore necessary to provide a seal which will maintain the sterility of the catheter and yet be easily removable. Such devices are well known in the art. However, it is also highly desirable to be able to administer small volume injections directly into the catheter or to take samplings of parenteral fluids needed between treatments directly from the catheter, thus avoiding the pain and discomfort accompanying direct insertion of hypodermic needles.
Previous devices for self-sealing injection ports have not been completely satisfactory where high back pressures are developed, or where catheters are left indwelling for a long period of time. The present invention relates to a device and method of constructing a device which provides improved self-sealing capabilities for injection ports used for small volume parenteral sampling and delivery systems and which is designed for ease of assembly during manufacture and yet it also relatively cheap to manufacture.
Accordingly, it is an object of the present invention to provide an improved self-sealing injection port for small volume parenteral sampling and delivery systems which permits a catheter to be kept indwelling for long periods of time in sterile condition and which is highly leak resistant under repeated use.
It is a further object of the present invention to provide an improved self-sealing injection port for small volume parenteral sampling and delivery systems which is useful for applications where high back pressures might be encountered, such as in a manifold system which is coupled to an infusion pump during chemotherapy treatments.
It is a still further object of the present invention to provide an improved self-sealing injection port used for small volume parenteral sampling and delivery systems which is easy to assemble during manufacture.
It is a still further object of the present invention to provide an improved self-sealing injection port used for small volume parenteral and delivery systems which is relatively cheap to manufacture and use.
These and other objects and advantages of the present invention will become more apparent in the following figures and detailed description.